From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752543Ab3LZCaQ (ORCPT ); Wed, 25 Dec 2013 21:30:16 -0500 Received: from mail-oa0-f48.google.com ([209.85.219.48]:45454 "EHLO mail-oa0-f48.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752477Ab3LZCaO convert rfc822-to-8bit (ORCPT ); Wed, 25 Dec 2013 21:30:14 -0500 Date: Wed, 25 Dec 2013 20:30:09 -0600 From: Rob Landley Subject: Question about /proc/uptime To: linux-kernel@vger.kernel.org Cc: Oleg Nesterov , Martin Schwidefsky X-Mailer: Balsa 2.4.11 Message-Id: <1388025009.1176.17@driftwood> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; DelSp=Yes; Format=Flowed Content-Disposition: inline Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org There are two values here, the first is seconds since boot time (which is just elapsed time; at one point it was ajusted for suspend and that was revered as confusing). The second value isn't documented but looking at fs/proc/uptime.c I think it's idle time? Except, if yo uadd up the idle time from all processors wouldn't you get 4x the uptime on a 4-way SMP system that's been idle since boot? Also, is this actual "cpu was on but not doing anything" time, so doesn't count suspend as idle? So if you subtract idle from uptime (on a uniprocessor system) on a system that spent some of its time suspended, what do you get? Amount of time the system "wasn't idle" means... Is suspend time idle or not idle? Confused, Rob